Another Improved Set : Slim Set

| In order to improve the eeciency of the Secure Electronic Transaction (SET) protocol, Hanaoka et al. proposed a light weight version of the SET protocol, called \LITESET"at ACISP '98. They claimed that LITESET has about 50% reduction in computational time and about 80% reduction in communication overhead by using a signcryp-tion scheme. We propose another way to construct an eecient SET protocol, called \Slim SET(SSET)". For acheiving the same security level and eeciency, SSET uses the domain-veriiable signcryption scheme that only predetermined n participants within the domain of protocol participants can decrypt their own part of message and verify the whole transaction. SSET is as eecient as LITESET, but doesn't require recipients' private keys for detection of dishonest acts.